High-temperature polybenzimidazole-based membranes

Polybenzimidazole (PBI)-based high-temperature proton exchange membranes (PEMs) offer many advantages that aid in a simplified fuel cell system design. Such benefits include high resistance to fuel impurities (most notably carbon monoxide), fast electrode kinetics, and simplified water and thermal management due to operational temperatures above 120 ◦C.[1] As a result of its intrinsic physicochemical properties, e.g., heat resistance and proton conductivity above 100 ◦C without humidification, PBI has emerged as a prime candidate for low-cost PEMs (see High-temperature membranes, Volume 3). Additionally, several PBI chemistries prepared through the polyphosphoric acid (PPA) process have been shown to possess improved characteristics and have overcome some of the limiting factors associated with conventionally prepared PBI membranes imbibed with phosphoric acid (PA) electrolyte. 4]